PA-34 Electrical Short Melted Rudder Cable

Piper PA-34-220T Seneca V G-OXFF of Oxford Aviation Academy was about to enter the runway for takeoff at Oxford Airport on 2 November 2018 when the instructor noticed the rudder pedals felt soft and was “too easy to move”.  The student confirmed they did not feel right, so they abandoned the planned flight and returned to the hangar for investigation.

Safety Investigation

The UK Air Accident Investigation Branch (AAIB) investigation report highlights the need for attention on EWIS (Electrical Wiring Interconnection Systems) of all sizes of aircraft:

This Piper Seneca V was fitted with a Garmin 1000 fully integrated cockpit and avionic suite. The system is reliant on electrical power and has a standby battery to keep the system running in the unlikely event of a twin-generator and main battery failure.

Inspection of the aircraft revealed the right rudder cable had chafed against the standby battery wiring and shorted to earth.

OAA PA-34 G-OXFF Chafed Wiring (Credit: AAIB)

OAA PA-34 G-OXFF Chafed Wiring (Credit: AAIB)

The heat generated by the electrical short had melted through the steel-braided rudder cable.

OAA PA-34 G-OXFF Severed Rudder Control Cable (Credit: AAIB)

OAA PA-34 G-OXFF Severed Rudder Control Cable (Credit: AAIB)

Safety Action

This potentially serious risk to airworthiness was brought to the attention of the manufacturer, the CAA, EASA and the FAA. The CAA took immediate steps to inform owners and operators of similarly configured Piper Seneca V aircraft.

The manufacturer has subsequently issued a mandatory Service Bulletin (No 1337) which gives instructions to reroute a portion of the emergency power wiring to improve the clearance from the rudder control cables.

OAA PA-34 Senecas at Oxford (Credit: Tl9380 at the English Wikipedia, GNU Free Documentation License)

Safety Resources

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